Sofa



FIG. 1 is a front view of a sofa showing my new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a top view thereof; and,

FIG. 4 is a bottom view thereof.

The fragmented crosshatching shown on the seat and backrest cushion is understood to represent fabric and would be continuous throughout the circumscribed areas. 

The ornamental design for a sofa, as shown and described. 